Electrochemical fuel cells using hydrogen and oxygen as reactant gases and a polymer electrolyte as the separator membrane are able to operate at high energy efficiency with virtually zero emission. In such fuel cells, water management has a significant impact on fuel cell performance. The polymer electrolyte membrane needs water to maintain a proper hydration level for sufficient ionic conductivity. On the other hand, water is produced on the cathode through the electrochemical reduction of oxygen. Water produced at the cathode is typically removed by evaporating into the gas flow channels next to the cathode. If the water is evaporated too slowly, however, the electrode will fill with liquid water (flood), preventing the reactant gas from reaching the catalyst in the cathode. Fuel cell reaction will slow down dramatically or stop completely if the cathode is flooded with water. During cold start or low temperature operation (such as in 0°-60° C. temperature range), the cathode is particularly prone to liquid water flooding.
US Patent Application Publication 20050271927 describes a method of forcing water to flow from the cathode to the anode by operating the cathode at a higher temperature than that of the anode. The cathode layer and the components of the cathode layer, such as the carbon, are manufactured to have higher thermal resistance.
A fuel cell typically includes a gas flow distributor plate which may have a single gas channel of serpentine design to maximize reactant gas contact with the electrode. The gas flow distributor plate also functions as an electric current collector and conductor in a fuel cell stack. A portion of the electricity generated by the fuel cell is lost to the internal electric resistances of the distributor plate. To minimize this parasitic energy drain, one typically seeks to maximize the contact area between the flow distributor plate and its neighboring components so that there is minimal electric contact resistance and thermal contact resistance. A solid plate material having high electrical conductivity is typically preferred.